The present invention relates to an accessory drive for a car with a transversely mounted engine.
In conventional cars with a transversely mounted engine, such as a car with a front engine front drive (abbreviated as FF car) or a car with a rear engine rear drive (abbreviated as RR car), an engine compartment has accommodated therein not only an engine, but also a transmission, a final drive, accessories and their associated devices. Nowadays, there is the tendency to arrange within the engine compartment accessories for an exhaust purifying device and an air conditioner. These accessories may include a thermal reactor, an air pump for the secondary air supply, a cooler compressor and a cooler condenser.
Therefore some difficulties have arisen in arrangeing the accessories for the exhaust purifying device and the air conditioner within the engine compartment.
To solve these it was proposed that the accessories be disposed on or adjacent the front end of a transversely mounted engine. However, employing such arrangement will require a transversely wide engine compartment.
Nowadays, it is proposed to use a space over a transmission installed adjacent the rear end of a transversely mounted engine for accommodation of such accessories in order to make the whole assembly in the engine compartment compact.
As some of the accesories must be driven by the engine, the constructional difficulty arises in driving them by the engine crankshaft if they are so arranged. It has been proposed to drive them from the engine cam shaft. However, the rotational speed of the cam shaft is half of the rotational speed of the crankshaft and is not high enough for driving the accessories thus requiring a step-up device using such as a gear drive or a belt drive. The use of the gear drive has a cost disadvantage because the manufacturing cost of gears are expensive, while the use of belt drive has a disadvantage that a large one of a pair of pulleys occupies a relatively large space.